Pre-Bottling Quality Control Molly Kelly Enology Extension Specialist Pennsylvania Winery Association Annual Meeting March 3, 2014 Bottling and Packaging • One of the most critical steps in wine production • Many opportunities for problems – People with different responsibilities – Multiple wines to bottle – Operation and maintenance of multiple equipment stations QA and QC • Quality Assurance (QA) focuses on attempts to improve and stabilize production practices in order to prevent defects • Quality Control (QC) focuses on product testing to uncover defects • HACCP: means of assuring quality, through the identification and monitoring of critical control points from vine to glass Pre-bottling checklist • Chemical analysis – Does wine meet proper criteria for bottling? • Stability analysis – Protein, bitartrate, color and microbiological stability • Sensory analysis • Materials – Present and in proper condition? Oxidation Potential • Review your bottling system (including pre-bottling filtration) to know the extent of oxygen pick-up • Optimally, the oxygen pick-up during any transfer, including bottling, =< 0.2 mg/L • Oxidation potential can be minimized • Particulates, case dust, adsorb air (oxygen) -increase the potential for oxidative degradation • The use of vacuum corkers, closure types, fill height, and the temperature of the wine at bottling impact the oxygen pick-up Chemical analysis Sulfur dioxide • The concentration of free sulfur dioxide that provides an anti-microbiological impact is determined by the pH • How much is based on the wine’s biological content, wine chemistry, and how much free sulfur dioxide is lost during your bottling operation • Excessive oxygen pick-up during the filtration and bottling, including lack of a vacuum system, reduces the sulfur dioxide concentration notably Stability Testing • This commonly includes protein, bitartrate and microbiological testing • A quantitative test for L-malic acid (vs. paper chromatography) will help assure that wines do not undergo MLF in the bottle • If there is a potential for Brettanomyces growth, a biological screening should occur Wines with malic acid • Paper chromatography • If malic acid is present it will be susceptible to MLF in the bottle • High SO2 levels at bottling and cool storage will reduce the chances of this happening • Sterile filtration can remove all bacteria and yeast Wines with residual sugar • Can measure with Clinitest tablets • Store under cool conditions (below 50F) to avoid stimulating yeast • Potassium sorbate can help prevent refermentation • Not 100% effective and can impart a bubblegum flavor to wine Turbidity Testing • If a wine is not brilliantly clear, it will likely plug membrane filters •Wines that do not clarify naturally should be tested for pectins and/or glucans •Polysaccharides can inhibit clarification, fining and filtration •Lab test: acidulated alcohol precipitation •Use of pectolytic enzymes and/or glucanases Sensory Evaluation • To be a true evaluation of structural, textural and aromatic elements, proper serving temperature and optimal glassware should be used • Prior to bottling a screen for sulfur like offodors should be conducted on all wines Sanitation • Anything in contact with the wine is a potential vector for microbial spoilage • Have appropriate sanitation protocols in place and implement them Sterile bottling rooms? • Not an absolute necessity • Bottling area should be screened-off from fermentation areas and excessive air movement • Easily sanitized floors, walls and ceilings Sources of contamination at bottling • Filter pad drip trays: drain often during runs • Fill bowls: leaky spouts. Mist filler spouts with 70% ethanol to inhibit microbial growth • Corker: likely to have spilled wine so large source of contamination. Dismantle and clean before and after. Ethanol misting of corker jaws during bottling • Activity: increased worker activity in bottling area increases spread of airborne microbes. Limit number of people around filling/corking area Bottling Quality Control • Wine Oxidation – Bottling can result in 0.5 to >2.0mg of oxygen per liter into the wine – Impacts wine quality and shelf life – To limit oxygen issues: • Sulfur dioxide adds prior to bottling • Nitrogen sparging • Carbon dioxide or nitrogen flushing bottles before filling Loss of Free Sulfur Dioxide • Is proportional to dissolved oxygen content • If not using vacuum fillers, corkers or flushing bottles with gas…up to 5 ml of air in bottle head space (750ml-1.4 mg of oxygen) • 4 mg of sulfur dioxide are needed to neutralize effects of 1 mg oxygen • So an additional 5-6 mg of free SO2 is needed to reduce oxygen in the head space Sulfur dioxide • Acetaldehyde formation is a direct result of oxygen exposure • Monitoring the free sulfur dioxide concentration could be an effective means of reviewing the impact of different closures and how a wine bottled with a certain closure is holding up • A periodic evaluation of the free sulfur dioxide level from random bottles is an effective gauge for monitoring wine development Sulfur Dioxide • As wines develop in the bottle and retain a level of free sulfur dioxide exceeding 13 mg/L, the likelihood of developing oxidized aroma/flavors is minimized • When the free sulfur dioxide level drops to less than about 13 mg/L, we can expect perceptible “developed” and/or oxidative aromas • A level of 13 mg/L or more free sulfur dioxide should be considered an average concentration. Different wines have differing oxidative buffering capacities (impacted by the total antioxidant concentration) • Antioxidants include phenols, ascorbic acid, sulfur dioxide, etc. Corks • Generally, corks transported at 20o C should be stored below 8% moisture • Water activity is low enough to inhibit mold growth • Treat corks with sulfur dioxide or purchase treated corks • Suppliers usually treat with SO2 gas or ionizing radiation Cork Questions • Are the corks bleached? • What is the moisture content when shipped? • How are they sterilized? • Do they remain sterile in your cellar? Oxygen in the Bottle • Can be highly variable • When the cork is compressed in the neck of the bottle, gas pressure in the cork cells can double, releasing oxygen trapped in the lenticels • In a 750-mL bottle, several tenths of a cubic centimeter of oxygen can be released during the first weeks of bottle aging • How much oxygen depends on several factors: including relative moisture content of the cork. The higher the cork moisture, the less oxygen is released Oxygen at Bottling • How much is desirable, and how much is excessive? More than 1.0 mg/L oxygen at bottling is not desirable for any wine • Lower concentrations are best for aromatic whites • Red wines, due to their higher buffering capacity, can withstand higher oxygen concentrations at bottling, up to about 0.7 mg/L • Factors influencing oxygen levels at bottling include wine temperature, bottling equipment, and closure type. Oxygen • If potential for oxidation is high, do not bottle cold • Increased solubility of oxygen • High oxygen levels are especially detrimental to wines with sorbic acid (potassium sorbate) • Develop oxidative products that are unpleasant Oxygen Penetration An example of oxygen penetration in closures: Screwcaps 0.0005 mg/L Natural cork 0.0179 mg/L Thus, oxygen ingress post-bottling is usually very limited, or near zero The exceptions include some synthetic closures Managing oxygen ingress • Nitrogen gas sparging pre- and/or postfilling • Liquid nitrogen sparging pre- and/or postfilling • Vacuum • Most oxygen quality control strategies only record dissolved oxygen in the wine, leaving headspace levels unmonitored Headspace management • 2006-2008 International Wine Challenge in London: almost half of wine faults were oxygen management related • AWRI Commercial Service and Normacorc: bottling line audit using PreSens® technology PreSens technology and wine bottle application (PreSens/Nomacorc, 2008). Normacorc/AWRI Commercial Service Practical winery and vineyard Oxoluminescence technology: headspace O2 and dissolved O2 Filter integrity • Perform frequent pressure holds • Bubble point • CUNO Minicheck (a 3M company) – Hand held device – Attach to housing and pressurize for certain time frame – Pass/fail Bubble Point The bubble point test detects minor filter defects and out-ofsize pores and correlates with the bacteria passage. Sartorius.com •Flood membrane with water •Pressurize to 80% with Nitrogen gas •Increase 2psi/min •Note pressure when bubbling starts and compare to filter specifications Millipore.com Millipore.com Continuous in-line monitoring Sample directly through MicropreSure® monitor via sanitary sampling valve Remove excess liquid remaining in dome with syringe Insert broth medium via the dome and remove excess media with syringe. Incubate the MicropreSure® monitor. Does not eliminate need for spot-checking bottles. Contamination can result downstream, especially at bottle filler. Millipore Corp. HACCP • Logical system of control based on the prevention of problems – – – – – Look at your process from start to finish Decide where hazards can occur Put in controls and monitor them Write it all down and keep records Ensure that it continues to work effectively • All wineries would benefit from a basic outline • http://www.apps.fst.vt.edu/extension/enology/EN/index.html What about mobile lines? Photo courtesy of Jennifer Foil Thank you for your attention. Questions? References • Bottling handbook for proper closures. Cork Quality Council, Forestville CA. http://www.corkqc.com/qcguidelines/qc.htm. Accessed Feb 26, 2013. • Lansing, R. May 2011. Managing Bottling Operations. Wine Business Monthly. • Neradt, F. 1982. Sources of reinfections during cold-sterile bottling of wine. Am. J. Enol. Vitic. Vol. 33. no. 3. • Pilone, G. 1977. Technical Note. Continuous inline monitoring of wine for yeast and bacteria. Am. J. Enol. Vitic. Vol 28, no. 4. • Pregler, B. Dec 2009. What’s Cool: Accurate Membrane Filter Integrity Testing. Wine Business Monthly. • Tracy, R. and Skaalen, B. Jan/Feb 2009. Bottling-last line of microbial defense. Practical Winery and Vineyard. • Ugliano, M., et al. 2013. Controlling oxygen at bottling to optimize post-bottling development in wine. Practical Winery and Vineyard. • Zoecklein, B. January 13, 2005. Enology Notes #97. Virginia Tech Wine and Grape Chemistry Group. • Zoecklein, B. February 17, 2005. Enology Notes #98. Virginia Tech Wine and Grape Chemistry Group. • Zoecklein, B. January 30, 2006. Enology Notes #111. Virginia Tech Wine and Grape Chemistry Group.